Background & Aims: Since previous studies on complications resulting from exposure to electromagnetic fields emitted by mobile phones are based only on self- reported symptoms, this study was performed to find the capability of users in recognition of real/ sham microwave exposure and probable alterations of vital signs after microwave exposure. Methods: In a two- step screening, from 700 students in Shiraz University of Medical Sciences and Shiraz University, 20 ones diagnosed as hypersensitive who had no significant exposure to other EMF sources, were selected and exposed twice to real and sham radiations each for 10 minutes and their self- reported symptoms were recorded. Then in the last stage their vital signs were recorded by connecting them to ICU monitoring devices. Results: Only problem in concentration and low back pain were associated with mobile phone use (P<0.05). Furthermore, there was a significant association between the location of mobile phone during talk and the overall score of the intensity of the symptoms (P<0.001). Only 5 students (25%) could discriminate the real /sham exposures. No statistically significant changes in means of vital signs in real/sham exposures were observed. Conclusion: Our findings clearly confirm the results obtained in other provocative studies. These data also indicate the possible role of psychological factors in electromagnetic hypersensitivity